Explosion-proof lightning arrester including conductive liquid to expedite formation of external shunt path

ABSTRACT

An explosion-proof lightning arrester structure includes active elements contained within an insulating housing which is provided at each end with an electrical fitting including a pressurerelief device and an associated gas-deflection outlet by means of which the discharged gas forms a temporary electrical bridge outside of the housing between the end fittings in shunt with the electrical circuit internally of the housing between these fittings. To expedite formation of the external shunt path, a spray cylinder is located at each gas-deflection outlet from which a jet of a conductive liquid is automatically released when the pressure-relief device responds and gas is discharged from the outlet.

United States Patent [193 Meier 1 1 EXPLOSION-PROOF LIGHTNING ARRESTER INCLUDING CONDUCTIVE LIQUID TO EXPEDITE FORMATION OF EXTERNAL SHUNT PATH [75] Inventor: Eugen Meier, Wettingen, Switzerland [73] Assignee: Aktiengesellschaft Brown, Boreri & Cie, Baden, Switzerland 221 Filed: May 19, 1972 21 Appl.No.: 254,915

[52] US. Cl. ..3l7/63, 337/30, 315/36, 317/61 [51] Int. Cl. ..H02h 1/04 [58] Field of Search ..317/65, 64, 63, 61; 315/36; 337/28, 30; 3l3/DIG. 5, 325

[ March 6, 1973 Primary Examiner.l. D. Miller Assistant Examiner-l-larvey Fendelman Attorney-Ralph E. Parker et al.

[57] ABSTRACT An explosion-proof lightning arrester structure includes active elements contained within an insulating housing which is provided at each end with an electrical fitting including a pressure-relief device and an associated gas-deflection outlet by means of which the discharged gas forms a temporary electrical bridge outside of the housing between the end fittings in shunt with the electrical circuit internally of the housing between these fittings. To expedite formation of the external shunt path, a spray cylinder is located at each gas-deflection outlet from which a jet of a conductive liquid is automatically released when the pressure-relief device responds and gas is discharged from the outlet.

6 Claims, 2 Drawing Figures QATENTEUHAR am; y 3,719,867

' SHEET 10F 2 Fig.1

PATENTEDHAR 6197a 3,719,867.

SHEET 2 BF 2 EXPLOSION-PROOF LIGHTNING ARRESTER INCLUDING CONDUGTIVE LIQUID TO EXPEDITE FORMATION OF EXTERNAL SHUNT PATH This invention relates to an explosion-proof lightning arrester the active parts of which are contained in an insulating housing provided with at least one pressurerelief and gas-deflecting device. I

The fitting of pressure-relief devices to the end of the insulating housing of a lightning arrester is known from German Pat. No. 1,290,241. In the event of fault conditions in the active part of the arrester these devices allow free egress to the gases forming in the insulating housing. By means of deflecting devices the gases are deflected outside the insulating housing in such a way that an external arc occurs, which greatly reduces the energy conversion inside the arrester. It is also known from German Pat. Nos. 1,049,488 and 1,063,698 to temporarily shunt electrical circuits in very high-voltage installations, using a conducting jet of liquid. Such arrangements are employed with switching devices to divert capacitive charges and induced voltages in the event of brief single-pole interruptions.

The principal object of the invention is to improve the explosion-resistance characteristic of lightning arresters by creating a device to transfer the fault arc very rapidly to the outside whereby, in particular when the arrester is relatively tall, an extremely short are transfer time can be achieved, thus substantially improving the range of application of the arrester.

This objective is achieved in that the pressure-relief device is connected to a device, located outside the insulating housing of the lightning arrester, which temporarily short-circuits the insulation of the insulating housing between its conductive end fittings by means of an electrically conductive liquid jet in such a way that the conductive liquid jet occurs when the pressure-relief device is tripped.

A preferred embodiment of the invention is illustrated by the accompanying drawings, in which:

FIG. 1 shows a sectional elevation of the improved lightning arrester; and

FIG. 2 shows a detail of the same on a larger scale.

In FIG. I the insulating housing is denoted l and contains the active parts 2 of the arrester which have not been further detailed since they are well known. The two ends of insulating housing 1 are provided with end closure fittings 3,4,10. Within fittings 3,4 are pressurerelief plates 5 and seal rings 50 which under normal conditions are spring loaded into contact with the end walls of the tubular insulating housing 1 thus tightly sealing it. The active parts 2 are electrically connected to fittings 3,4 in a known manner and hence not further described. The closure plate 5 for each end of the tubular insulating housing 1, in addition to being spring loaded to its closed position, is seen to be coupled by a control lever 6 pivotally mounted at 7 to an actuating rod 9 which functions to release a spring-loaded piston 12 within a spray cylinder assembly 8,8 which expells a bridging conductive liquid jet from the end of the cylinder whenever the closure plate 5 is lifted off the end of housing 1. Thus, two liquid jets moving in opposite directions strike one another and thus complete the desired electrical bridging effect between the opposite ends of the arrester structure within a very short time. However, the arrester structure is capable of operating in the desired manner with only one of the spray cylinders.

The arrester operates in the following manner. When a fault are occurs inside of the arrester housing during the surge-diverting process, the pressure build-up thus created causes the pressure-relief plates 5 to lift off the ends of the housing l. The gas thus released from opposite ends of housing 1 and delivered into the spaces 3a, 4a defined by the end fittings 3, 4 which are spaced from the ends of housing 1, is deflected and passes to the exterior of housing I through discharge outlets 3b, 4b which are aligned with each other in the direction P and within which the spray cylinder assemblies 8, 8 are located. Movement of plates 5 actuate the corresponding control levers 6 which move rods 9 from the position shown in the right half of FIG. 2 to the position shown in the left half. In the position illustrated in the right half, it will be seen that a head 14 at the end of rod 9 presses in a radially outward direction against the detent ends 13a of a plurality of cantilever spring latching members 13 to hold the detents 13a engaged with a circumferential recess 12a provided in a piston 12 slidable within cylinder ill. Piston I2 is spring-loaded in the direction ofthe discharge end of cylinder 11 by means of a stack of annular plate springs 15 which surround the cantilever spring members 13 but is restrained against movement so long as the head 14 of rod 9 is in the position illustrated in the right half of FIG. 2. In this position, a supply of the conductive liquid is stored within a chamber 16 between piston 12 and the lower tapered discharge end of cylinder 11 which includes a discharge orifice 11a closed by plug 17. However, when rod 9 is shifted to the position illustrated in the left half of FIG. 2, detents 1311 are released thus permitting the lower ends of the cantilever spring members 13 to be moved radially inward thereby to release piston 12 for movement toward the discharge end of cylinder 11 under the force exerted by the stack of precompressed plate springs 15. Movement of piston 12 creates a pressure upon the conductive liquid stored within chamber 16 which is sufficient to eject plug 17 and cause a jet of liquid to be expelled from the discharge orifice. The spray cylinder assembly 8' at the opposite end of the arrester and located in alignment with spray cylinder 8 functions in the same manner, with the result that two jets of conductive liquid are expelled towards one another as are also the gas discharges from outlets 3a, 3b and when they meet, the desired conductive bridge is formed outside of housing 1 in parallel with the potential existing inside of the housing between the conductive end fittings 3 and 4, whereby the fault are occurring inside of the arrester housing 1 is very quickly transferred to the outside. The stress in the interior of the arrester is thus quickly relieved, and the arrester is prevented from exploding. The spray cylinder assembly is usually replaced after one operation.

I claim:

1. In an explosion-proof lightning arrester structure the active parts of which are contained within an insulating housing provided with conductive end fittings and provided with at least one gas-deflecting outlet and pressure-relief device, the improvement which includes means responsive upon actuation of said pressure-relief device for establishing a jet of a conductive liquid between said end fittings in the gas-deflection path thereby to temporarily short-circuit the insulating housing and expedite transfer of the fault arc to the exterior of the housing.

2. An explosion-proof lightning arrester structure as defined in claim 1 wherein said means for establishing said jet of conductive liquid between said end fittings is constituted by a spray cylinder assembly located in said gas-deflection path comprising a cylinder for storing therein a quantity of the conductive liquid, and including a discharge orifice for the liquid, a spring-loaded piston for effecting expulsion of the liquid jet from said discharge orifice and means controlled by actuation of said pressure-relief device for effecting the release of said piston.

3. An explosion-proof lightning arrester structure as defined in claim 2 wherein said means controlled by actuation of said pressure-relief device for effecting release of said piston includes a lever actuated by said pressure relief device, and a rod connected to and operated by said lever, said rod extending longitudinally into said cylinder and including a head cooperable with latching members engageable with said piston.

4. An explosion-proof lightning arrester structure as defined in claim 3 wherein said latching members are constituted by cantilever spring members surrounding said rod and which include detent means at the ends thereof engageable with a circumferentially extending recess within said piston.

5. An explosion-proof lightning arrester structure as defined in claim 4 wherein the spring-loading for said piston is constituted by a stack of annular plate springs surrounding said cantilever spring members, one end of said stack of plate springs being fixed in position and the opposite end bearing against said piston.

6. An explosion-proof lightning arrester structure as defined in claim 2 and wherein said discharge orifice from said spray cylinder is sealed by a plug ejectable automatically upon movement of said piston. 

1. In an explosion-proof lightning arrester structure the active parts of which are contained within an insulating housing provided with conductive end fittings and provided with at least one gas-deflecting outlet and pressure-relief device, the improvement which includes means responsive upon actuation of said pressure-relief device for establishIng a jet of a conductive liquid between said end fittings in the gas-deflection path thereby to temporarily short-circuit the insulating housing and expedite transfer of the fault arc to the exterior of the housing.
 1. In an explosion-proof lightning arrester structure the active parts of which are contained within an insulating housing provided with conductive end fittings and provided with at least one gas-deflecting outlet and pressure-relief device, the improvement which includes means responsive upon actuation of said pressure-relief device for establishIng a jet of a conductive liquid between said end fittings in the gas-deflection path thereby to temporarily short-circuit the insulating housing and expedite transfer of the fault arc to the exterior of the housing.
 2. An explosion-proof lightning arrester structure as defined in claim 1 wherein said means for establishing said jet of conductive liquid between said end fittings is constituted by a spray cylinder assembly located in said gas-deflection path comprising a cylinder for storing therein a quantity of the conductive liquid, and including a discharge orifice for the liquid, a spring-loaded piston for effecting expulsion of the liquid jet from said discharge orifice and means controlled by actuation of said pressure-relief device for effecting the release of said piston.
 3. An explosion-proof lightning arrester structure as defined in claim 2 wherein said means controlled by actuation of said pressure-relief device for effecting release of said piston includes a lever actuated by said pressure relief device, and a rod connected to and operated by said lever, said rod extending longitudinally into said cylinder and including a head cooperable with latching members engageable with said piston.
 4. An explosion-proof lightning arrester structure as defined in claim 3 wherein said latching members are constituted by cantilever spring members surrounding said rod and which include detent means at the ends thereof engageable with a circumferentially extending recess within said piston.
 5. An explosion-proof lightning arrester structure as defined in claim 4 wherein the spring-loading for said piston is constituted by a stack of annular plate springs surrounding said cantilever spring members, one end of said stack of plate springs being fixed in position and the opposite end bearing against said piston. 